Call:
lm(formula = y ~ x)

Residuals:
     Min       1Q   Median       3Q      Max 
-0.03687 -0.02145 -0.01745  0.00855  0.48297 

Coefficients:
                       Estimate Std. Error t value          Pr(>|t|)    
(Intercept)           0.0214527  0.0028329   7.573 0.000000000000115 ***
xLow income          -0.0006735  0.0063766  -0.106           0.91592    
xLower middle income  0.0119701  0.0051276   2.334           0.01985 *  
xNA                  -0.0055318  0.0097695  -0.566           0.57142    
xUpper middle income  0.0154169  0.0047354   3.256           0.00119 ** 
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

Residual standard error: 0.04947 on 707 degrees of freedom
Multiple R-squared:  0.02138,	Adjusted R-squared:  0.01584 
F-statistic: 3.861 on 4 and 707 DF,  p-value: 0.004117