stat collector is not using

I am using Postgresql 8.1.

I set stats_start_collector = on

But I found statistics collector is not using;

show stats_start_collector;
stats_start_collector
-----------------------
on
(1 row)

select * from pg_stat_user_indexes where idx_scan > 0;
relid | indexrelid | schemaname | relname | indexrelname | idx_scan |
idx_tup_read | idx_tup_fetch
-------+------------+------------+---------+--------------+----------+--------------+---------------
(0 rows)

select * from pg_stat_user_tables where seq_scan > 0;
relid | schemaname | relname | seq_scan | seq_tup_read | idx_scan |
idx_tup_fetch | n_tup_ins | n_tup_upd | n_tup_del
-------+------------+---------+----------+--------------+----------+---------------+-----------+-----------+-----------
(0 rows)

select * from pg_stat_user_indexes where relname='crm';

relid | indexrelid | schemaname | relname |
indexrelname | idx_scan | idx_tup_read | idx_tup_fetch
---------+------------+------------+------------------+---------------------------------+----------+--------------+---------------
2587873 | 2593637 | public | crm |
crm_smownerid_deleted_idx | 0 | 0 | 0
2587873 | 2593636 | public | crm |
crm_deleted_smownerid_idx | 0 | 0 | 0
2587873 | 2593635 | public | crm |
crm_modifiedby_idx | 0 | 0
| 0
2587873 | 2593634 | public | crm |
crm_smownerid_idx | 0 | 0
| 0
2587873 | 2593633 | public | crm |
crm_smcreatorid_idx | 0 | 0
| 0
2587873 | 2593631 | public | crm
| crm_pkey | 0
| 0 | 0

Could anyone please tell me why the statistics collector is not using?

I run vacuum analyze every night.