I'm surprised the statistical information you started compiling doesn't exist. I'm from Alberta and our professional association (APEGGA) compiles this information on a yearly basis. The statistics from May 2008 included over 12,000 data points. Similar information is available from some (and maybe all) of the other provincial associations.
The main page for the APEGGA Salary survey is:
APEGGA Salary Survey Main Page
There are two documents. The summary is 2 pages long but the complete document is probably a hundred pages. The summary is found here:
Salary Survey Summary
I've copied below the relevant information from the "Total Compensation - Engineers - All Industries" table. In Alberta a fully qualified P.Eng would generally be rated C-Level or higher.
Level_ Sample_ %Change____ Mean__ 1stDecile__ 1stQuartile_____ Median______ 3rdQuartile_____ 9thDecile
A-____ 447___ 4.4%___ 46,606.00____ 39,376.00____ 42,640.00____ 46,800.00____ 49,647.00____ 53,400.00
A___ 1,278___ 3.4%___ 66,239.00____ 52,109.00____ 58,344.00____ 63,600.00____ 72,400.00____ 81,983.00
B___ 1,478___ 5.9%___ 79,162.00____ 61,512.00____ 67,959.00____ 75,600.00____ 84,775.00____ 95,512.00
C___ 1,829___ 5.1%___ 95,818.00____ 74,184.00____ 83,473.00____ 92,873.00____ 102,544.00___ 117,518.00
D___ 2,331___ 7.7%___ 126,162.00___ 91,200.00____ 104,424.00___ 118,312.00___ 136,034.00___ 172,570.00
E___ 2,006___ 5.7%___ 155,884.00___ 112,170.00___ 128,892.00___ 148,200.00___ 171,520.00___ 197,588.00
F___ 1,185___ 4.7%___ 194,036.00___ 133,510.00___ 153,500.00___ 180,000.00___ 213,479.00___ 266,760.00
F+ _ 471_____ 5.2%___ 281,139.00___ 157,391.00___ 185,000.00___ 216,800.00___ 284,790.00___ 422,750.00