Table:
text: List of cities in Punjab, Pakistan by area
Punjab
Punjab
Serial_No_ District Headquartered_City City_Population_2009 City_Areakm_2_
14 Kasur District Kasur City 314617 18
15 Khanewal District Khanewal City 165038 17
16 Khushab District Jauharabad City 38475 12
17 Lahore District Lahore City 6936563 462
18 Layyah District Layyah City 82734 10
19 Lodhran District Lodhran City 93232 08
20 Mandi Bahauddin District Mandi Bahauddin City 150980 09
21 Mianwali District Mianwali City 93659 20
22 Multan District Multan City 1566932 133
23 Muzaffargarh District Muzaffargarh City 158597 15
24 Nankana Sahib District Nankana Sahib City 60137 06
25 Narowal District Narowal City 74417 07
26 Okara District Okara City 232386 21
27 Pakpattan District Pakpattan City 136510 14

Question: What is the sum of serial numbers for Narowal city in list of cities in Punjab, Pakistan by area?