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:
| No. | # | Title | Directed by | Written by | U.S. air date | Production code | U.S. viewers (million) |
| --- | --- | --- | --- | --- | --- | --- | --- |
| 196.0 | 1.0 | "Lazarus" | Kevin G. Fair | Don Whitehead & Holly Henderson | September24,2010 | 3X6001 | 2.98 |
| 197.0 | 2.0 | "Shield" | Glen Winter | Jordan Hawley | October1,2010 | 3X6002 | 2.38 |
| 198.0 | 3.0 | "Supergirl" | Mairzee Almas | Anne Cofell Saunders | October8,2010 | 3X6003 | 2.30 |
| 199.0 | 4.0 | "Homecoming" | Jeannot Szwarc | Brian Peterson & Kelly Souders | October15,2010 | 3X6004 | 3.19 |
| 200.0 | 5.0 | "Isis" | James Marshall | Genevieve Sparling | October22,2010 | 3X6005 | 2.60 |
| 201.0 | 6.0 | "Harvest" | Turi Meyer | Al Septien & Turi Meyer | October29,2010 | 3X6007 | 2.96 |
| 202.0 | 7.0 | "Ambush" | Christopher Petry | Don Whitehead & Holly Henderson | November5,2010 | 3X6006 | 2.63 |
| 203.0 | 8.0 | "Abandoned" | Kevin G. Fair | Drew Landis & Julia Swift | November12,2010 | 3X6008 | 2.90 |
| 204.0 | 9.0 | "Patriot" | Tom Welling | John Chisholm | November19,2010 | 3X6009 | 2.60 |
| 205.0 | 10.0 | "Luthor" | Kelly Souders | Bryan Q. Miller | December3,2010 | 3X6010 | 2.76 |
| 206.0 | 11.0 | "Icarus" | Mairzee Almas | Genevieve Sparling | December10,2010 | 3X6011 | 2.55 |
| 207.0 | 12.0 | "Collateral" | Morgan Beggs | Jordan Hawley | February4,2011 | 3X6012 | 2.37 |
| 208.0 | 13.0 | "Beacon" | Mike Rohl | Don Whitehead & Holly Henderson | February11,2011 | 3X6013 | 2.32 |
| 209.0 | 14.0 | "Masquerade" | Tim Scanlan | Bryan Q. Miller | February18,2011 | 3X6014 | 2.22 |
| 210.0 | 15.0 | "Fortune" | Christopher Petry | Anne Coffell Saunders | February25,2011 | 3X6015 | 2.56 |
| 211.0 | 16.0 | "Scion" | Al Septien | Al Septien & Turi Meyer | March4,2011 | 3X6016 | 2.18 |
| 212.0 | 17.0 | "Kent" | Jeannot Szwarc | Brian Peterson & Kelly Souders | April15,2011 | 3X6018 | 2.37 |
| 213.0 | 18.0 | "Booster" | Tom Welling | Geoff Johns | April22,2011 | 3X6017 | 2.35 |
| 214.0 | 19.0 | "Dominion" | Justin Hartley | John Chisholm | April29,2011 | 3X6021 | 1.99 |
Question:
On which date did episode # 18 air in the U.S.?
Answer:
April22,2011