How many themes have the original artist of Judy Garland?
{'header': ['Week #', 'Theme', 'Song choice', 'Original artist', 'Order #', 'Result'], 'page_title': 'Jason Castro (singer)', 'page_id': '', 'types': ['text', 'text', 'text', 'text', 'text', 'text'], 'id': '1-15796100-1', 'section_title': 'Performances', 'caption': 'Performances', 'rows': [['Top 24 (12 Men)', '1960s', '" Daydream "', "The Lovin' Spoonful", '11', 'Safe'], ['Top 20 (10 Men)', '1970s', '" I Just Want to Be Your Everything "', 'Andy Gibb', '2', 'Safe'], ['Top 16 (8 Men)', '1980s', '" Hallelujah "', 'Leonard Cohen', '7', 'Safe'], ['Top 12', 'Lennon–McCartney', '" If I Fell "', 'The Beatles', '4', 'Safe'], ['Top 11', 'The Beatles', '" Michelle "', 'The Beatles', '8', 'Safe'], ['Top 10', 'Year They Were Born', '" Fragile "', 'Sting', '2', 'Bottom 3'], ['Top 9', 'Dolly Parton', '" Travelin\' Thru "', 'Dolly Parton', '4', 'Safe'], ['Top 8', 'Inspirational Music', '" Over the Rainbow "', 'Judy Garland', '3', 'Safe'], ['Top 7', 'Mariah Carey', '" I Don\'t Wanna Cry "', 'Mariah Carey', '7', 'Safe'], ['Top 6', 'Andrew Lloyd Webber', '" Memory "', 'Elaine Paige', '2', 'Safe'], ['Top 5', 'Neil Diamond', '" Forever in Blue Jeans " "September Morn"', 'Neil Diamond', '1 6', 'Safe']], 'name': 'table_15796100_1'}