How can I change the width/thickness of a scrollbar?

Currently this is my scrollbar.xml file:

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" >

    <gradient
        android:angle="45"
        android:centerColor="@color/blue"
        android:endColor="@color/blue"
        android:startColor="@color/blue" />

    <corners android:radius="8dp" />

</shape>

And this is my ScrollView:

<ScrollView
    android:id="@+id/scrollView1"
    android:scrollbarThumbVertical="@drawable/scrollbar"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_alignParentBottom="true"
    android:layout_alignParentLeft="true"
    android:layout_alignParentRight="true"
    android:layout_below="@+id/btnBack" >

This is the scrollbar it gives me. It's good, except it's too thick and obvious. It may not look thick in this screenshot, but it really is.

Am I able to set a ScrollView property to adjust the width/thickness of the scrollbar? Or can I put a property in my gradient?

add the following property to your layout

android:scrollbarSize="50dip"