Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
What is the total number of total viewers with a share of 18.8% and a weekly ranking under 16?

### Inputs:
table_name: table, columns: ['Episode No.', 'Airdate', 'Total Viewers', 'Share', 'BBC One Weekly Ranking']

### Response:
SELECT COUNT Total Viewers FROM table WHERE Share = 18.8% AND BBC One Weekly Ranking < 16