The per capita consumption (in pounds) of all beef in the United States is given by the function $C(x)=-0.33 x+67.1,$ where $x$ is the number of years since $2000 .$ (Source: Based on data from the Economic Research Service, U.S. Department of Agriculture, $2000-2008$ )
a. Find and interpret $C(4)$.
b. Estimate the per capita consumption of beef in the United States in $2010 .$