Average of SUMIF with 2 criteria

[thetoader]

Hello:

I am working in Microsoft Excel 2007. I have a data table and am trying to find the average of a two criterias being met if possible.

Column Headings
A = Companies (cell range is A4:A8000)
B = Total Assets of Companies (Cell range is R4:R8000)
C = Total cost of Health Ins. plans (cell range is AS4:AS8000)

I have different categories and want to find the number for each:
I have found how many companies with over $100Million in assets have health insurance plans.

=SUMIF($R$4:$R$8000,">="&A9,$AS$4:$AS$8000)
A9 is where my category list starts (A9=1000000000)

I want to find the average assets of those stores with over $100Million in asset size AND have an insurance plan. Some of the stores have "0" for health insurance plans.

My categories are:
over 100M
50M-100K
25M-50M
and so on down to under 100 Thousand

I hope I've made sense.

Thanks!