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:
| Series # | Season # | Title | Directed by | Written by | Original air date | Total viewers (in millions) |
| --- | --- | --- | --- | --- | --- | --- |
| 45.0 | 1.0 | "The Day After" | Michael Lange | Patrick Sean Smith | August31,2009 | 1.211 |
| 46.0 | 2.0 | "Our Fathers" | Patrick Norris | Jessica O’Toole & Amy Rardin | September7,2009 | 1.313 |
| 47.0 | 3.0 | "The Half-Naked Gun" | Michael Lange | Roger Grant | September14,2009 | N/A |
| 48.0 | 4.0 | "High and Dry" | Shawn Piller | Casey Johnson | September21,2009 | N/A |
| 49.0 | 5.0 | "Down on Your Luck" | Michael Lange | Matt Whitney | September28,2009 | N/A |
| 50.0 | 6.0 | "Lost and Founders" | Fred Gerber | Michael Berns | October5,2009 | N/A |
| 51.0 | 7.0 | "The Dork Knight" | Rick Rosenthal | Adam Milch | October12,2009 | N/A |
| 52.0 | 8.0 | "Fight the Power" | Michael Lange | Jessica O’Toole & Amy Rardin | October19,2009 | N/A |
| 53.0 | 9.0 | "The Wish-Pretzel" | Melanie Mayron | Lana Cho & Matt Whitney | October26,2009 | N/A |
| 54.0 | 10.0 | "Friend or Foe" | Michael Lange | Roger Grant | November2,2009 | N/A |
| 55.0 | 11.0 | "I Know What You Did Last Semester" | Michael Lange | Casey Johnson & David Windsor | January25,2010 | N/A |
| 56.0 | 12.0 | "Pride & Punishment" | John T. Kretchmer | Jessica O’Toole & Amy Rardin | February1,2010 | N/A |
| 57.0 | 13.0 | "Take Me Out" | Lee Rose | Matt Whitney | February8,2010 | N/A |
| 58.0 | 14.0 | "The Tortoise and the Hair" | Michael Lange | Rob Bragin | February15,2010 | N/A |
| 59.0 | 15.0 | "Love, Actually, Possibly, Maybe... Or Not" | Mark Rosman | Roger Grant | February22,2010 | 0.872 |
| 60.0 | 16.0 | "Your Friends and Neighbors" | Michael Lange | Dana Greenblatt | March1,2010 | 0.937 |
| 61.0 | 17.0 | "The Big Easy Does It" | Fred Savage | Casey Johnson & David Windsor | March8,2010 | 1.031 |
| 62.0 | 18.0 | "Camp Buy Me Love" | Michael Lange | Jessica O’Toole & Amy Rardin | March15,2010 | 0.820 |
| 63.0 | 19.0 | "The First Last" | Patrick Norris | Roger Grant & Matt Whitney | March22,2010 | N/A |
Question:
What is the total number of titles written by Casey Johnson?
Answer:
1.0