<apex:page controller="ChartController">
    <apex:chart height="400" width="700" data="{!data}">
        <apex:legend position="right"/>
        <apex:axis type="Numeric" position="left" fields="data1"  title="Percentage %" grid="true"/>
        <apex:axis type="Category" position="bottom" fields="name"  title="Month of the Year">
            <apex:chartLabel rotate="315"/>
        </apex:axis>
        <apex:lineSeries title="Closed-Won" axis="left" xField="name" yField="data1"  fill="true" markerType="cross" markerSize="4" markerFill="#FF0000"/>
    </apex:chart>
</apex:page>

----------Controller---------



public class ChartController {
      
    public List<Data> getData() {
        List<Data> data = new List<Data>();
        data.add(new Data('Jan', 90));
        data.add(new Data('Feb', 82));
        data.add(new Data('Mar', 74));
        data.add(new Data('Apr', 66));
        data.add(new Data('May', 58));
        data.add(new Data('Jun', 50));
        data.add(new Data('Jul', 42));
        data.add(new Data('Aug', 34));
        data.add(new Data('Sep', 26));
        data.add(new Data('Oct', 18));
        data.add(new Data('Nov', 10));
        data.add(new Data('Dec', 0));
        return data;
    }

    
    public class Data {
        public String name { get; set; }
        public Integer data1 { get; set; }
        
        public Data(String name, Integer data1) {
            this.name = name;
            this.data1 = data1;
            
        }
    }
    
    
}