The Foundation Center provides this free database where you can find data on grants given per year, including dollar value of those grants, by subject areas. This database also allows you to view data by population groups and recepient location. Additional statistics include aggregate grant fiscal data and top grant givers.
The Nonprofit Almanac 2012
Provides data from 2000 to 2010 on financial and employment trends in the nonprofit sector and attempts to evaluate the role of nonprofits in the U.S. economy.
Blackbaud - Nonprofit Industry Research
Blackbaud is a publically traded company which provides software, services and training to nonprofits.