Inflation has obediently averaged a 2.1 percent annual rate since 2010, albeit with some big swings. Every month, the Bureau of Labor Statistics reports the change in the consumer price index. The part of the index followed by the Federal Reserve - all items less food and energy - increased only 0.1 percent for the month and 1.9 percent for the previous 12 months. The Federal Reserve watches inflation in its particular way because food and energy prices are volatile and can overstate the general rate of inflation. The cost of shelter is the largest item in the consumer price index, accounting for nearly 32 percent of it. The figure is calculated with a complex blending of rents and homeowner equivalent rents. The next-largest spending categories, medical care and transportation, at 5.8 and 5.5 percent of the CPI-U, were mixed bags over the last year. Motor vehicle maintenance and repairs rose only 1.6 percent.