On July 17, 2008, what was the total number of lead maragin? 
CREATE TABLE table_16751596_13 (lead_maragin VARCHAR, dates_administered VARCHAR)
SELECT COUNT(lead_maragin) FROM table_16751596_13 WHERE dates_administered = "July 17, 2008"
<s>[INST] Write mssql query to answer the following question given the database schema. Schema: CREATE TABLE table_16751596_13 (lead_maragin VARCHAR, dates_administered VARCHAR) Question: On July 17, 2008, what was the total number of lead maragin?  [/INST] SELECT COUNT(lead_maragin) FROM table_16751596_13 WHERE dates_administered = "July 17, 2008" </s>