Along with incomes, people's charitable contributions have steadily increased over the past few years. the table below shows the average deduction for
charitable contributions reported on individual income tax returns for the period 1993 to 1998. find the average annual increase between 1995 and 1997.

year charitable contributions
1993 $1900
1994 $2450
1995 $2470
1996 $2850
1997 $3010
1998 $3140

a. $270 per year
b. $280 per year
c. $335 per year
d. $540 per year