how many company were founded in the same year as dentsply sirona ?
select attr_open count attr_open distinct var_uri attr_close as var_c attr_close where brack_open var_uri rdf_type dbo_Company sep_dot var_uri dbo_foundingYear var_year sep_dot dbr_Dentsply_Sirona dbo_foundingYear var_year sep_dot dbr_Dentsply_Sirona a dbo_Companybrack_close