ITEM 7. MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS
You should read the following discussion together with Item 6. “Selected Financial Data” and our consolidated financial statements and related notes included in Item 8. “Financial Statements and Supplementary Data.” The discussion contains forward-looking statements involving risks, uncertainties and assumptions that could cause our results to differ materially from expectations. Factors that might cause such differences include those described in Item 1A. “Risk Factors” and elsewhere in this report.
Steve Ells, our founder, Chairman and CEO, started Chipotle with the idea that food served fast did not have to be a typical fast food experience. Today, we continue to offer a focused menu of burritos, tacos, burrito bowls, and salads made from fresh, high-quality raw ingredients, prepared using classic cooking methods and served in an interactive style allowing people to get what they want. We seek out extraordinary ingredients that are not only fresh, but that are raised responsibly, with respect for the animals, land, and people who produce them. We prepare our food using real, wholesome ingredients and without the use of artificial colors or flavors typically found in fast food. Chipotle opened with a single restaurant in Denver in 1993 and as of December 31, 2017, we operated 2,408 restaurants.
Sales. Our sales and profitability improved during 2017 as compared to 2016. Comparable restaurant sales increased 6.4% as a result of an increase in the average check, including a 1.2% benefit from menu price increases implemented in about 500 restaurants during the second quarter of 2017 and 900 restaurants during the fourth quarter of 2017. Comparable restaurant sales represent the change in period-over-period sales for restaurants beginning in their 13th full calendar month of operation. Average restaurant sales were $1.940 million as of December 31, 2017, increasing from $1.868 million as of December 31, 2016. We define average restaurant sales as the average trailing 12-month sales for restaurants in operation for at least 12 full calendar months. We expect comparable restaurant sales increases in the low single digits for the full year 2018, including the benefit from extending menu price increases to almost 950 additional restaurants in January 2018. Sales growth from new restaurant openings, however, will be lower in 2018 than in the past due to our planned decrease in new restaurant openings during the year, as discussed below under “Restaurant Development.”
During 2017, we invested in improving our digital platforms, including significant improvements to our mobile application and online ordering platform, and equipping select restaurants with an upgraded second make line dedicated to fulfilling out-of-restaurant orders. Sales from out-of-restaurant orders represented 8.3% of our revenue during the year ended December 31, 2017, up from 6.4% of revenue during the year ended December 31, 2016. Additionally, in September 2017 we introduced an all-natural queso, which was ordered in approximately 10% of our transactions in January 2018.
Restaurant Operating Costs. During the full year 2017, our restaurant operating costs (food, beverage and packaging; labor; occupancy; and other operating costs) as a percent of revenue decreased 4.1% compared to the full year 2016. The decrease was attributable to sales leverage, including the benefit of the menu price increases, lower marketing and promotional spend as a percent of revenue, and labor efficiencies, partially offset by higher wages paid to crew and managers.
Restaurant Development. As of December 31, 2017, we had 2,408 restaurants in operation, including 2,363 Chipotle restaurants throughout the United States, with an additional 37 international Chipotle restaurants and eight non-Chipotle restaurants that were consolidated into our financial results. We opened 183 restaurants in 2017, including two relocations, and closed 23 additional restaurants (including 15 ShopHouse Southeast Asian Kitchen restaurants). We intend to open between 130 and 150 restaurants for the full year 2018, as we focus our resources on improving our operations and delivering an outstanding experience to every one of our guests. Most of our 2018 restaurant openings are planned in markets that already have a Chipotle presence established.
Tax Law Changes. In December 2017, the Tax Cuts and Jobs Act was signed into law, and among other changes, the Act lowered the U.S. corporate income tax rate from 35% to 21% beginning in 2018. As a result, we recognized a $6.0 million benefit in our provision for income taxes related to the remeasurement of our deferred tax position at the lower rate.
We expect our 2018 annual effective tax rate to be in the range of 30% to 31%, which includes an underlying effective tax rate of 27% to 28%, and around 3% to 4% related to stock awards. As discussed in Note 1. “Description of Business and Summary of Significant Accounting Policies” included in Item 8. “Financial Statements and Supplementary Data,” the adoption of ASU No. 2016-09, “Compensation-Stock Compensation (Topic 718)” will subject our tax rate to quarterly volatility from the effect of stock award exercise and vesting activities. Additionally, we have deferred tax assets related to outstanding non-vested stock awards that contain market conditions. If market conditions are not achieved, then we may not realize the benefit of these deferred tax assets, which would result in a higher effective tax rate in future periods. We believe the stock awards granted in 2015 and 2016 that contain market conditions will increase our tax rate in the first and fourth quarters of 2018, respectively.