It would certainly appear so, according to these charts, comparing listings at Spamhaus to GDP. CAUCE thanks furio ercolessi who thought to do the comparison.

update: Rob Szarka rightly points out that these are the largest economies, not the world's richest nations.

Country Live Spam Issues At Spamhaus.org
1 United States 2,370
2 China 898
3 Russian Federation 559
4 United Kingdom 380
5 Japan 258
6 Brazil 254
7 Canada 242
8 France 222
9 Italy 216
10 Germany 214
   
   
Country GDP in Billions of $
 United States  $14,620,000
 China  $5,745,000
 Japan  $5,391,000
 Germany  $3,306,000
 France  $2,555,000
 United Kingdom  $2,259,000
 Italy  $2,037,000
 Brazil  $2,024,000
 Canada  $1,564,000
 Russia  $1,477,000