Prefix distribution: refinement of prefix trees

Prefix type breakdown
(semiglobal prefixes in 26 tables, Nov.01,2001)
standalone          44264     42.75%
root                           5601       5.41%
more specifics    53686     51.84%
total prefixes     103551  100.00%

Percentage of root prefixes grows slowly 
1999   4.64
2000   4.86
2001   5.41

Another refinement phenomenon:
growing share of the table is roots 
constant or decreasing share of more specifics
average number of subblocks of a root is decreasing