Add prefix/suffix public property for y label values

@@ -46,6 +46,12 @@ typedef NSString *(^PNYLabelFormatter)(CGFloat yLabelValue);
 /** Formats the ylabel text. */
 @property (copy) PNYLabelFormatter yLabelFormatter;
 
+/** Prefix to y label values, none if unset. */
+@property (nonatomic) NSString *yLabelPrefix;
+
+/** Suffix to y label values, none if unset. */
+@property (nonatomic) NSString *yLabelSuffix;
+
 @property (nonatomic) CGFloat chartMargin;
 
 /** Controls whether labels should be displayed. */

@@ -119,7 +119,7 @@
     label.font = _labelFont;
     label.textColor = _labelTextColor;
     [label setTextAlignment:NSTextAlignmentRight];
-    label.text = labelText;
+    label.text = [NSString stringWithFormat:@"%@%@%@", _yLabelPrefix, labelText, _yLabelSuffix];
     [self addSubview:label];
     
     [_yChartLabels addObject:label];