Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_name_74 ( year INTEGER, opponent_in_the_final VARCHAR )

### Question ###
How many years have an Opponent in the final of welby van horn?

### Accurate SQL ###

SELECT SUM(year) FROM table_name_74 WHERE opponent_in_the_final = "welby van horn"