Texas House Rental - Annual Return?

[John Clark]

I have considered buying houses ($150-200K value) in Texas for rental income. However I'm not impressed with my expected annual return. If someone could help me with my analysis; it would be much appreciated. Below is the math (all in % of house value):

Rent: 12.0%
Taxes: -2.8%
Average Long-Term Maintenance & Repairs: -1.7%
House Insurance & HOA: -1.6%
Average Vacancy/FinderFees/Tenant Issues: -1.0%
Property Management: -0.8%
Total Average Annual Return: 4.1%

I have heard landlords making 10% (no leverage) and 20-30% (with leverage). What am I missing?