feat(index-hit-rate): adds 5 decimal places to output value

[mgartner]

Before

$ psql_lob_api -f sql/index_hit_rate.sql
Expanded display is used automatically.
          relname          | percent_of_times_index_used | rows_in_table
---------------------------+-----------------------------+---------------
 tracking_events           | 99                          |     470658857
 addresses                 | 99                          |     328110020
 trackings                 | 99                          |     223399192
 sam_routes                | 100                         |     110832574
 verifications             | 99                          |      96260955
 letters                   | 99                          |      96100351
 postcards                 | 99                          |      63465479
 checks                    | 99                          |       4784045
 us_zip_lookups            | 100                         |       2944461
 sam_areas                 | 100                         |       2051983
 statements                | 99                          |       1355389
 route_demographics        | 100                         |        639185
 accounts_keys             | 100                         |        544269
 bank_account_sequences    | 100                         |        427475
 template_versions         | 100                         |        252361
 templates                 | 99                          |        189348
 users                     | 99                          |        140096

After

$ psql_lob_api -f sql/index_hit_rate.sql
Expanded display is used automatically.
          relname          | percent_of_times_index_used | rows_in_table
---------------------------+-----------------------------+---------------
 tracking_events           |                   100.00000 |     470658857
 addresses                 |                   100.00000 |     328109835
 trackings                 |                   100.00000 |     223399076
 sam_routes                |                   100.00000 |     110832506
 verifications             |                    99.49227 |      96260953
 letters                   |                    99.99999 |      96100280
 postcards                 |                    99.99999 |      63465436
 checks                    |                    99.99991 |       4784043
 us_zip_lookups            |                   100.00000 |       2944461
 sam_areas                 |                   100.00000 |       2051982
 statements                |                    99.99856 |       1355389
 route_demographics        |                   100.00000 |        639185
 accounts_keys             |                   100.00000 |        544269
 bank_account_sequences    |                   100.00000 |        427475
 template_versions         |                   100.00000 |        252361
 templates                 |                    99.99998 |        189348
 users                     |                    99.98901 |        140096
...

[vinay-pad]

LGTM