How many French heads of state have a head of mission of Xavier Daufresne de la Chevalerie?
create table table_29474481_4 (french_head_of_state varchar, head_of_mission varchar, PRIMARY KEY (french_head_of_state))
select count(french_head_of_state) from table_29474481_4 where head_of_mission = "xavier daufresne de la chevalerie"