Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Release | Artist | Title | Notes | Album |
| --- | --- | --- | --- | --- |
| 2004 | Hiroshi Itsuki feat. Rimi Natsukawa | Deigo to Hanasu (デイゴとはまなす Talking with a Tiger's Claw Flower?) |  | Onna no Ehon |
| 2005 | Chikuzen Sato with Rimi Natsukawa | Boku no Mune de Oyasumi (僕の胸でおやすみ Goodbye with My Heart?) | Features on "Rimits: Best Duet Songs" (2006) | The Selection of Cornerstones 1995-2004 |
| 2005 | Rimi Natsukawa | 'Aa Kōshien' Kimi yo Hachigatsu ni Atsuku Nare (「あゝ甲子園」君よ八月に熱くなれ You Make Me Hot in August (from Ah, Kōshien)?) |  | Ningen Manyōka: Yū Aku Kashishū |
| 2005 | Kaoru Kurosawa duet with Rimi Natsukawa | Manten no Hoshi no Yoru (満天の星の夜 Night with a Sky Full of Stars?) | Features on "Rimits: Best Duet Songs" (2006) | Love Anthem |
| 2006 | Andrea Bocelli duet with Rimi Natsukawa | Somos Novios (Ai no Yume) (ソモス・ノビオス～愛の夢 It's Impossible (Dream of Love)?) | Features on "Umui Kaji" (2007) | Amore (Japanese Edition) |
| 2008 | Taiyo Yamazawa presents Rimi Natsukawa | Utabito (歌人 Singer?) |  | Music Tree |
| 2009 | Chage with Rimi Natsukawa | Boku wa Dō Kana (僕はどうかな What Should I Do?) |  | Many Happy Returns |
| 2009 | Rimi Natsukawa | Tada Sore Dake (ただそれだけ It's Only That?) |  | Katsuhisa Hattori |
Question:
how many titles have only one artist?
Answer:
2